HEALTH CARE

Schering Agrees to Buy U.S. Firm: The German drug maker said it agreed to acquire Medrad Inc., a Pennsylvania maker of vascular injection systems used in medical imaging, for about $180 million, or $28 a share. Last spring, Medrad retained Dillon Read & Co. and Parker Hunter Inc. to explore strategic options that included making acquisitions or selling the company. Medrad shares closed up $5.375 at $27.625 in Nasdaq trading. Schering, based in Berlin, said Medrad shareholders have 20 business days to accept its tender offer, which is expected early next week. The acquisition of Medrad, which had revenue of $78.3 million last year, would strengthen its diagnostic products business, Schering said.